Introduction to Matter

Introduction

Various types of substances can be found in our surrounding. Some substances are very simple whereas some are very complex. Some substances can be broken into other simpler substances while some substances cannot be broken. A substance which cannot be further broken down into other simpler substances is called an element. Hydrogen, oxygen, nitrogen, chlorine, mercury, lead, etc. are the examples of the element. There are altogether 109 elements known so far. Out of them, 92 elements are naturally found and remaining 26 elements are artificially prepared by scientists. Elements combine together to form a new substance, which is called a compound. Salt, water, chalk, carbon dioxide, etc. are the examples of a compound.

Atom

An atom is the smallest particle of an element which can take part in a chemical reaction. They are different in size, masses, and chemical properties. For example atoms of hydrogen are similar in all respects whereas the atoms of oxygen elements are different. 118 elements have 118 different types of atoms. So, different elements have different atoms.

Molecule

The smallest particles of an element or compound are called molecule. For example, a molecule of chlorine is made of two atoms of chlorine, it is denoted by Cl. The molecule of a compound contains two or more atoms of different elements. For example, a molecule of water (H₂O) contains two atoms of hydrogen and one atom of oxygen. It is represented by H₂O.